Silicon-On-Insulator (SOI) substrates may be fabricated by a process known as separation by implantation of oxygen (SIMOX). A large part of the cost to fabricate SOI substrates is the time required to implant oxygen by an ion implanter. Quality, thickness and uniformity of the top silicon layer, quality, thickness and uniformity of the buried oxide layer, silicon defect thickness above the buried oxide layer are variables in the SOI substrates resulting from the particular SIMOX fabrication process used.
There is an increasing interest in low-dose (LD) SIMOX to reduce the time of implantation and thus the cost of SOI substrates. The lower dose results in less machine time required to implant the oxygen. Furthermore, the structural and electrical quality of the Si active layer improves in the LD SIMOX material. The standard procedures used for LD SIMOX typically have the following deficiencies: (1) a buried oxide (BOX) breakdown voltage V.sub.bd Of less than 8 MV/cm, (2) electrical shorts such as 5 to 10 shorts cm.sup.-2, (3) Si islands within the BOX of 10.sup.3 to 10.sup.4 islands cm.sup.-2, and (4) a rough Si surface.